First published online June 22, 2006
Development 133, 1405e (2006)
© The Company of Biologists Limited
Neural map making revisited
To transmit unbroken images, retinal axons must terminate on their target
brain region in the correct relative positions to form a retinotopic map. On
p. 2705, David
Willshaw presents a new computationally generated model for retinotopic map
formation using data from mouse EphA receptor knockin and knockout
experiments. Neural map formation is thought to involve two steps: an
activity-independent step, which uses position-specific molecular labels to
establish a crude map of where retinal axons should migrate, and an
activity-dependent mechanism, which refines the map. From his analysis of
experimental data, Willshaw concludes that the guiding principle behind
retinotopic mapping is that axons carrying similar amounts of Eph receptor
terminate near each other on their target and activity-based mechanisms only
function later in development. He shows that the 30-year-old marker induction
model (in which fixed retinal labels induce labels on tectal cells) can
simulate EphA receptor knockin and knockout experiments. Finally, he proposes
a refined model - the `retinal induction model' - in which the retinal and
tectal labels are Ephs and ephrin ligands, respectively.
Related articles in Development:
- Analysis of mouse EphA knockins and knockouts suggests that retinal axons programme target cells to form ordered retinotopic maps
- David Willshaw
Development 2006 133: 2705-2717.
[Abstract]
[Full Text]
